Mobile terminals, such as mobile phones and tablet computers, often allow screen rotation for rotating an image displayed on a screen. For example, a user may change a screen, orientation, of a mobile terminal by rotating the mobile terminal. Conventionally, a mobile terminal has a built-in gravity sensor to determine a current posture of the mobile terminal. When the mobile terminal is positioned in or close to a standard posture, i.e., an upright posture, the screen has an upright portrait orientation. When the mobile terminal rotates, the screen rotates accordingly to a left landscape orientation, a reverse portrait orientation, or a right landscape orientation.
However, such method of controlling screen orientation presumes that the user always stands or sits upright while using the mobile terminal, and therefore may cause undesirable screen rotations when the user is in other postures. For example, when the user browses pictures on the mobile terminal while lying on a bed, the mobile terminal is positioned horizontally and the screen may often rotate undesirably.